1. Field of the Invention
This invention relates to hydraulic positive displacement machines, and more particularly to planetary hydraulic motors.
2. Prior Art
There are known planetary hydraulic motors comprising gear pairs of inner engagement and sealing assemblies of a rotating shaft. However, the above sealing assemblies fail to ensure reliable and durable operation of the hydraulic motors at high pressures in their interiors (cf. B. N. Birjukov "Rotary Hydraulic Machines" in Russian, published in 1972 by the Mashinostroenie Publishers, Moscow, see p. 28, FIG. 19; USSR Inventor's Certificate No. 449178, IPC F04C 1/00, published in Bulletin "Discoveries, Inventions, Industrial Designs and Trade Marks" No. 41, 1974--in Russian; and USSR Inventor's Certificate No. 595536, IPC F04C 1/00, published in Bulletin "Discoveries, Inventions, Industrial Designs and Trademarks" No. 8, 1978--in Russian).
A planetary hydraulic motor which is closest in its technical essence to the one claimed in this invention is exemplified in USSR Inventor's Certificate No. 696179, IPC F04C 1/00, published in Bulletin "Discoveries, Inventions, Industrial Designs and Trademarks" No. 41, 1979--in Russian. This planetary hydraulic motor comprises a housing with a stator gear, one side of the stator gear being covered by a cup intended for mounting the motor, the other side thereof being covered by a cup for feeding the motor with a working fluid. The housing incorporates a shaft having fixedly secured thereon a gear, a sealing assembly of the shaft in the form of a thrust ring disposed in the cup for mounting the motor, and a sleeve member having a cylindrical projection adjoining by the end face surface thereof the working surface of the thrust ring, the thrust ring being fabricated from fluoroplastic.
The above planetary hydraulic motor also comprises a ring rotor disposed eccentrically relative to the shaft to meshingly engage with the shaft gear and the stator gear, the stator gear and the outer toothing of the ring rotor forming a transmission gear pair, while the shaft gear and the inner toothing of the ring rotor define a gear pair having working chambers to feed the working fluid thereinto and discharge it therefrom, the working fluid being delivered from a valving mechanism including a fluid distributor fixedly secured on the shaft, and a valve disposed in the cup for feeding the working fluid.
Inherent in the known planetary hydraulic motors operating under high internal pressures and susceptible to radial beats of the shaft is a disadvantage residing in that the thrust ring wears out prematurely. This is accounted for by the fact that part of the fluoroplastic ring projected into a radial gap tends to be crumpled and damaged due to the beatings of the shaft resulting in a failure of the thrust ring. Therefore, the aforedescribed sealing assembly fails to provide reliable and durable operation of the planetary hydraulic motor.